Technical Field
The present disclosure relates to a plasmonic scattering nanomaterial comprising a substrate layer, a metal oxide layer and silver nanoparticles. The present disclosure further relates to a method for producing the nanomaterial. Additionally, the present disclosure relates to an application of the plasmonic scattering nanomaterial as a component of a thin film plasmonic solar cell.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Thin film solar cells have the potential to significantly decrease the cost of photovoltaic solar driven electric power generation. But unfortunately so far none of the technology has been able to challenge the supremacy of bulk crystalline silicon based cells, which possess a number of advantages such as high performance, stability, abundance in nature and non-toxicity. To achieve large scale implementation, the light harvesting efficiency must be further improved, especially through better light management. In conventional silicon (Si) based solar cells, surface texturing is considered for this purpose [U. Kreibig, M. Vollmer, Optical properties of metal clusters, Springer-Verlag, Berlin, 1995; and E. Yablonovitch, G. D. Cody, Intensity enhancement in textured optical sheets for solar cells, IEEE Trans. Electr. Dev. 29: 300-305, 1982; and H. W. Deckman, C. B. Roxlo, E. Yablonovitch, Maximum statistical increase of optical absorption in textured semiconductor films, Opt. Lett. 8: 491-493, 1983.—each incorporated herein by reference in its entirety]. Such geometries are not suitable for thin film cells because of geometrical constraints as well as the higher carrier recombination that occurs in the larger surfaces as well as at junctions.
An exciting way of achieving efficient light management in thin film solar cells is to introduce plasmonic nanoparticles and/or nanostructures that support surface plasmons defined as excitations of the conduction electrons at the interface between a metal and dielectric or at the surface of the nanoparticles and/or nanostructures. Until recently studies have focused on the increase of absorption in thin film solar cells through the surface plasmon effect [B. Rech, H. Wagner, Potential of amorphous silicon for solar cells, App. Phys. A 69: 155-167, 1999; and D. S. Shen, H. Chatham, P. K. Bhat, High-deposition-rate amorphous silicon solar cells: Silane or Disilane?, Solar Cells 30: 271-275, 1991; and H. A. Atwater, A. Polman, Plasmonics for improved photovoltaic devices, Nat. Mat. 9: 205-213, 2010; and M. K. Hossain, Y. Kitahama, G. G. Huang, T. Kaneko, Y. Ozaki, SPR and SERS characteristics of gold nanoaggregates with different morphologies, App. Phys. B 93: 165-170, 2008.—each incorporated herein by reference in its entirety]. Gold, silver or copper nanoparticles, ranging from 10 to 120 nm have been deposited by different techniques such as, wet processes or thermal evaporation followed by a heat treatment to generate islands. However, even if an increase in short circuit current has been demonstrated all of the works have underlined the necessity to improve the control of the nanoparticle properties (i.e., size, shape, surface density) to enhance solar absorption and to tune the plasmon resonance to a given wavelength range.
Plasmonics can offer at least three ways to enhance the efficiency: (i) as a subwavelength scattering element to couple and trap free plane waves into absorption layers [K. Imura, H. Okamoto, M. K. Hossain, M. Kitajima, Visualization of localized intense optical fields in single gold-nanoparticle assemblies and ultrasensitive Raman active sites, Nano Lett. 6: 2173-2176, 2006; and K. R. Catchpole, A. Polman, Plasmonic solar cells, Opt. Express 16: 21793-21800, 2008; and O. L. Muskens, J. G. Rivas, R. E. Algra, E. P. A. M. Bakkers, A. Lagendijk, Design of light scattering in nanowire materials for photovoltaic applications, Nano Lett. 8: 2638-2642, 2008.—each incorporated herein by reference in its entirety], (ii) as an inducer of polariton modes that confine and guide the light in the absorption layer [M. K. Hossain, Y. Kitahama, V. P. Biju, T. Kaneko, T. Itoh, Y. Ozaki, Surface plasmon excitation and surface-enhanced Raman scattering using two-dimensionally close-packed gold nanoparticles, J. Phys. Chem. C 113: 11689-11694, 2009; and M. K. Hossain, T. Shimada, M. Kitajima, K. Imura, H. Okamoto, Near-field Raman imaging and electromagnetic field confinement in the self-assembled monolayer array of gold nanoparticles, Langmuir 24: 9241-9244, 2008; and M. K. Hossain, T. Shimada, M. Kitajima, K. Imura H. Okamoto, Raman and near-field spectroscopic study on localized surface plasmon excitation from the 2D nanostructure of gold nanoparticles, J. Microsc. 229: 327-330, 2008.—each incorporated herein by reference in its entirety], and (iii) as an antenna that stores incident energy resulting in enhanced photocurrent.
A representative configuration is shown in FIG. 1. Typically the plasmonic structure is embedded in an active layer, such as silicon (Si), an intrinsic conductor and therefore, the plasmonic properties will be used to contribute to exciton generation. A recent concern has been designing and fabricating such geometries with hands-on techniques that can offer all of these benefits to achieve ultimate efficiency comparable to crystalline silicon solar cells [V. E. Ferry, J. N. Munday, H. A. Atwater, Design considerations for plasmonic photovoltaics, Adv. Mater. 22: 4794-4808, 2010; and K. Nakayama, K. Tanabe, H. A. Atwater, Plasmonic nanoparticle enhanced light absorption in GaAs solar cells, Appl. Phys. Lett. 93: 121904-1-121904-3, 2008; and C. F. Bohren, D. R Huffman, Absorption and scattering of light by small particles (Wiley, 2008); and J. Mertz, Radiative absorption, fluorescence, and scattering of a classical dipole near a lossless interface: a unified description. J. Opt. Soc. Am. B, 17:1906-1913, 2000; and D. Derkacs, W. V. Chen, P. M. Matheu, S. H. Lim, P. K. L. Yu, E. T. Yu, Nanoparticle-induced light scattering for improved performance of quantum-well solar cells, Appl. Phys. Lett. 93: 091107-1-091107-3, 2008.—each incorporated herein by reference in its entirety]. Since the plasmonic structures involved in such cases are an integral part of the complete solar cell, it is preferable to include post-processes as little as possible. Any modification in plasmonic structures will affect other layers and thus the entire performance of the cell will need to be revisited. A tunable and suitable plasmonic characteristic of such structures is desired beforehand. Cost effective and large scale fabrication as well as industrial production capabilities of such solar cells is a key factor in minimizing cost per kW. Although several issues such as interfaces enriched with carrier recombination, complicated processes to achieve plasmonic structures, etc. are inevitable, there is always room to improve the current technology. Nano-science and nanotechnology based understanding has paved the way for solar cell research by leaps and bounds already.
In view of the forgoing, one object of the present disclosure is to provide silver nanoparticles on metal oxide for consideration as a plasmonic scattering nanomaterial suitable for plasmonic photovoltaic solar cells. A further aim of the present disclosure is to provide a simple two-step and hands-on method for fabricating the nanomaterial. A further aim of the present disclosure is to provide a thin film plasmonic solar cell comprising the nanomaterial. The contributions of silver nanoparticles to plasmonic solar cells and an understanding of their beneficial characteristics as well as the simple fabrication method are indispensable to moving plasmonic solar cells forward to meet the challenges of the solar cell market.